Life Cycle Assessment (LCA) of Alternative Pavement Rehabilitation Solutions: A Case Study

Round 1

Reviewer 1 Report

Line 57: “It is worth mentioning that the idea of LCA was first taken up around 1970”- Citation required

Lines 58-59: “the studies of LCA were mainly conducted to analyze consumer products or materials and components of daily life”- Citation required

Lines 239 to 242: “The design period for the rehabilitated pavement was considered to be 24 years and the starting point of time was set to be the first design period. The first time period for the maintenance of the rehabilitated pavement section is estimated after 241 the first 12 years…”-

What informed this consideration?

Are there existing studies or industry standards that can be cited? Or was the PaLATE 2.0 used for inventory analysis?

 

How can future researchers estimate the design and maintenance periods in years and get a generalizable outcome?

This should be sufficiently clarified because these parameters are the hallmark of the research design and methodology.

Lines 360 to 361: “Consequently, it is clear that even a limited inclusion of recycled materials could  reduce the environmental footprint of a road project..” The authors should re-phrase this statement as it may misinterpreted to mean that the inclusion of recycled materials in pavement construction should be limited.

Lines 386 to 387: “The addition of 40% RAP in the unbound layer obviously reduces the amounts of all effect categories to a greater or lesser extent…” Using greater and lesser in the same sentence is confusing. Please clarify or modify. Does the addition of RAP in the unbound layer reduce the effect categories to a greater extent or a lesser one? It can be either, but not both.

Lines 398 to 400: “In this context, the incorporation of recycled materials into pavement sections produced by recycled methods should be common practice in the future, so further research in this scientific area is needed…”

This study has addressed this gap to a certain extent. Please include a) limitations of this study and b) areas of further research that can improve current methodology or address this study's limitations

Author Response

The authors would like to thank the reviewer for his/her valuable comments. Detailed answers are provided below.

 

Line 57: “It is worth mentioning that the idea of LCA was first taken up around 1970”- Citation required

Reply: Thank you for the comment. Please see line 57.

 

Lines 58-59: “the studies of LCA were mainly conducted to analyze consumer products or materials and components of daily life”- Citation required

Reply: Thank you for the comment. Please see lines 58-59.

 

Lines 239 to 242: “The design period for the rehabilitated pavement was considered to be 24 years and the starting point of time was set to be the first design period. The first time period for the maintenance of the rehabilitated pavement section is estimated after 241 the first 12 years…”-

What informed this consideration?

Reply: Thank you for the comment. Please see lines 246-251.

 

Are there existing studies or industry standards that can be cited? Or was the PaLATE 2.0 used for inventory analysis?

Reply: Thank you for the comment. Please see lines 272-273.

 

How can future researchers estimate the design and maintenance periods in years and get a generalizable outcome?

This should be sufficiently clarified because these parameters are the hallmark of the research design and methodology.

Reply: Thank you for the comment. Please see lines 246-251.

 

Lines 360 to 361: “Consequently, it is clear that even a limited inclusion of recycled materials could reduce the environmental footprint of a road project...” The authors should re-phrase this statement as it may misinterpreted to mean that the inclusion of recycled materials in pavement construction should be limited.

Reply: Thank you for the comment. Please see lines 379-380.

 

Lines 386 to 387: “The addition of 40% RAP in the unbound layer obviously reduces the amounts of all effect categories to a greater or lesser extent…” Using greater and lesser in the same sentence is confusing. Please clarify or modify. Does the addition of RAP in the unbound layer reduce the effect categories to a greater extent or a lesser one? It can be either, but not both.

Reply: Thank you for the comment. Please see lines 407-409.

 

Lines 398 to 400: “In this context, the incorporation of recycled materials into pavement sections produced by recycled methods should be common practice in the future, so further research in this scientific area is needed…”

This study has addressed this gap to a certain extent. Please include a) limitations of this study and b) areas of further research that can improve current methodology or address this study's limitations

Reply: Thank you for the comment. Please see lines 420-433.

Reviewer 2 Report

1. Some figures are in low resolution, e.g. Figure 1. Please provide clear figure.

2. Figures 3 and 4 can be deleted. The information can be textual.

5. List the inadequacies of current researches and the innovations of this article point by point in the introduction. Here, the reviewer recommends the following articles for the author's references:

Gas sealing behavior of gasketed segmental joints in shield tunnels: An experimental and computational study

Three-dimensional coupled hydromechanical analysis of localized joint leakage in segmental tunnel linings

Author Response

The authors would like to thank the reviewer for his/her valuable comments. Detailed answers are provided below.

1. Some figures are in low resolution, e.g. Figure 1. Please provide clear figure.

    Reply: Thank you for the comment. The Figure quality has been improved.

2. Figures 3 and 4 can be deleted. The information can be textual.

    Reply: Thank you for the comment. Please see new Figure 3 and lines 284-295.

5. List the inadequacies of current researches and the innovations of this article point by point in the introduction.

   Reply: Thank you for the comment. Please see lines 67-78.

Here, the reviewer recommends the following articles for the author's references:

Gas sealing behavior of gasketed segmental joints in shield tunnels: An experimental and computational study

Three-dimensional coupled hydromechanical analysis of localized joint leakage in segmental tunnel linings

   Reply: Thank you for the comment. Please see lines 59-61 and 457-462.

 

Reviewer 3 Report

Comments for author File: Comments.pdf

Author Response

The authors would like to thank the reviewer for his/her valuable comments. Detailed answers are provided below.

 

In short, this paper is a case study (can be considered a small technical paper but not a research paper) about upgrading pavement section using conventional materials and recycled materials (RAP) by conducting a life cycle assessment. Overall, the paper is well written and contribute to pavement sustainability. However, there are some issues that need to be addressed properly and in detail.

1- The novelty and the importance of the work is not clear. Please add a paragraph at the end of the introduction section.

Reply: Thank you for the comment. Please see lines 67-78.

 

2- The section “introduction” and “review of related studies” must be combined.

Reply: Thank you for the comment. The “review of related studies” has been renamed as “Background”.

 

3- The status of the pavement under study should be described in details and why it needs to be upgraded.

Reply: Thank you for the comment. Please see lines 227-229.

 

4- Why the design period for the rehabilitated pavement was considered to be 24 years? Please add a reference.

Reply: Thank you for the comment. Please see lines 246-251.

 

5- Line 271 – 273. What is the rationale behind selecting a milling depth of 120 mm?

Reply: Thank you for the comment. Please see lines 282-284.

 

6- Line 274 – “the total thickness of asphalt layer is 150 mm”. why? Any reference? What types of vehicle/trucks are expected to be loaded on this pavement section?

Reply: Thank you for the comment. Please see lines 227-229 and 282-284.

 

7- As the authors did not conduct any experimental tests in their study, it is imperative to describe all inputted parameter in the software used. (Physical and mechanical properties of RAP, etc.). otherwise, the LCA analysis in this work can’t be replicated.

Reply: Thank you for the comment. Please see lines 268-270 and the new Table 1.

 

8- Although LCA analysis is main objective to this study, the parameter “cost” is completely omitted in this study. The decision to select scenario 1 or 2 depends not only on LCA, but also on cost among other factors.

Reply: Thank you for the comment. Please see lines 423-428.

 

9- Line 363 – what are the existing techniques that must be modified, that the authors are referring to?

Reply: Thank you for the comment. Please see lines 380-386.

 

10- This study is very specific and limited as it is case study. The authors need to add a few sentences about its limitation?

Reply: Thank you for the comment. Please see lines 420-433.

Round 2

Reviewer 3 Report

the authors properly addressed my comments and significantly improved the quality of the paper. I have no further comments.